The Invidia Full Titanium Cat-Back Exhaust for the 2015+ Subaru WRX and WRX STi is a single exit racing style exhaust for drivers seeking the most power and weight reduction. Since the system is 100% full titanium you can expect that dry exhaust sound found in only titanium systems and since it only has one muffler you can expect a very loud tone. Piping is a full 80 mm (3.15 inches) with a blue burnt 101 mm (3.98 inches) tip!